Effect of Welding Procedure on the Fatigue Resistance of High-Strength Steel Butt-Welded jointsThursday (28.05.2020) 15:10 - 15:30
Experimental and analytical analyses were carried out in order to assess fatigue behaviour of high-strength steel butt-welded joints. Samples were manufactured with steel S960MC and S960QT and different welding techniques: Gas Metal Arc Welding (GMAW), Laser Hybrid Welding (LHW) and Electron Beam Welding (EBW). Fatigue tests were performed under the four points bending scheme, with stress ratio R = 0.1. All specimens showed fatigue crack initiation and subsequent growth from the weld toe area, near the heat affected zone (HAZ), although different S-N curves were obtained for the different welding procedures. Residual stresses, microstructure, hardness and joint geometry resulting from each technique were analysed and their effect on the fatigue resistance of the welds was evaluated by means of an integrated fracture mechanics methodology. This approach was applied to estimate the relative influence of the different geometrical and mechanical parameters of the weld. Joint geometry was found to be the most influencing factor.